<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>后盾人</title>
  </head>
  <body>
    <button message="后盾人" class="red">后盾人</button>
    <button message="hdcms">hdcms</button>
  </body>
  <script>
    let arr = [1, 3, 43];
    let res = arr.filter(item => {
      return item > 39;
    });
    // console.dir();
    console.log(res);
    let btns = document.querySelectorAll("button");
    btns = [].filter.call(btns, item => {
      return item.hasAttribute("class");
    });
    console.log(btns);
  </script>
</html>
